Method and apparatus for detecting blood in shell eggs

Abstract

An egg inspecting apparatus ( 1 ) of the present invention includes an optical path switching and projecting assembly ( 30 ) for automatically selecting one of a plurality of optical paths through which a white source light ( 11 ) emitted from a light source ( 2 ) is guided and also for sequentially projecting the white source light ( 11 ) from the associated optical paths onto eggs held at respective positions, a spectrum converting assembly for spectrally analyzing light which has been transmitted through each of the eggs and converting it into a spectrum, and a determining circuit ( 5 ) for determining whether the egg is a normal egg or a bloody egg by using the spectrum so converted. By way of example, a spectrum of an egg is measured and a secondary differential curve is formulated for classification of the eggs according to egg shell colors. By comparing a spectral pattern of the transmitted light of the egg with that of a normal egg for each of the shell colors, and assaying a pattern similarity by means of a correlational assay method, whether the egg is a normal egg or a bloody egg can be determined.

1. An egg inspecting apparatus which comprises:
 an optical path switching and projecting assembly for automatically selecting one of a plurality of optical paths through which a white source light emitted from a common light source is guided and also for sequentially projecting the white source light from the associated optical paths onto eggs held at respective positions; 
 a spectrum converting assembly for spectrally analyzing light which has passed through each of the eggs and converting it into a spectrum; and 
 a determining circuit for determining whether the egg is a normal egg or a bloody egg by using the spectrum so converted. 
 
   
   
     2. The egg inspecting apparatus as claimed in  claim 1 , wherein the optical path switching and projecting means includes an automatic optical path selector for sequentially guiding the white source light into one of the optical paths by means of a drive of a rotational angle control motor. 
   
   
     3. The egg inspecting apparatus as claimed in  claim 1 , wherein each of the optical paths is defined by an optical fiber. 
   
   
     4. The egg inspecting apparatus as claimed in  claim 1 , wherein the spectrum converting assembly includes a light receiver for receiving the light which has been transmitted through one of the eggs, and a spectral analyzing and light receiving unit for spectrally analyzing the transmitted light and for converting a light signal into an electric signal to thereby output a spectrum, said light receiver and said spectral analyzing and light receiving unit being coupled with each other through an optical fiber, and
 wherein spectra of the eggs are sequentially measured by transmitting the light, having passed through the eggs and subsequently received by the light receiver, to the spectral analyzing and light receiving unit through the optical fiber. 
 
   
   
     5. The egg inspecting apparatus as claimed in  claim 4 , wherein a center axis of the light receiver for receiving the light transmitted through the egg is inclined relative to a center axis of the source light used to illuminate the egg such that for avoiding an erroneous operation of a light receiving element of the spectral analyzing and light receiving unit in the absence of the egg at an inspecting site, the light receiver will not receive directly the source light of an intensity exceptionally higher than the intensity of the transmitted light. 
   
   
     6. The egg inspecting apparatus as claimed in  claim 1 , wherein the determining circuit is operable to determine if the egg is a normal egg or a bloody egg, by classifying an egg shell color by utilization of a spectrum of light reflected from an outer surface of an egg shell as a result of illumination of the egg with the source light and then utilizing the spectrum of the transmitted light having passed through the egg. 
   
   
     7. An egg inspecting method which comprises the steps of:
 automatically selecting one of a plurality of optical paths through which a white source light emitted from a common light source is guided to thereby project sequentially the white source light from the associated optical paths onto eggs held at respective positions; 
 spectrally analyzing light which has passed through each of the eggs to thereby convert it into a spectrum; and 
 determining whether the egg is a normal egg or a bloody egg by using the spectrum so converted. 
 
   
   
     8. The egg inspecting method as claimed in  claim 7 , wherein the step of determining whether the egg is a normal egg or a bloody egg is such that after the intensity of a spectrum of the light that has been transmitted through each egg has been divided by the intensity of a spectrum of the source light emitted from the light source and such divided intensity has been converted into a light transmittance, the spectrum of the transmitted light is normalized by the light transmittance at the wavelength of light little absorbed by a component of the respective egg and, then, a secondary differential curve of the spectrum is formulated to classify the egg shell color according to a peak intensity of a spectral absorption band exhibited by protoporphyrin, which is a pigment of an egg shell, and thereafter at a different spectral absorption band exhibited by hemoglobins contained in the bloody egg, in reference to a similarity between a spectral pattern of the egg and a spectral pattern of a normal egg having no blood, whether the egg inspected is a bloody egg or not is determined for each of the classified egg shell colors. 
   
   
     9. An egg grading and packaging system including the egg inspecting apparatus as defined in  claim 1 , which apparatus has loaded therein a computer-executable program to thereby render the system to have a capability of rejecting bloody eggs by automatically inspecting presence or absence of those bloody eggs while the eggs are transported successively. 
   
   
     10. An egg inspecting apparatus which comprises:
 a projecting assembly for projecting a white light, emitted from a light source, onto eggs; 
 a spectrum converting assembly including a light receiver for receiving light transmitted through each of the eggs and a spectral analyzing and light receiving unit for spectrally analyzing the transmitted light and converting a light signal into an electric signal to provide a spectrum; and 
 a determining circuit for measuring the spectrum of the transmitted light having passed through the egg, after a spectrum of light transmitted through a normal egg having no blood contained therein has been measured and recorded for each of egg shell colors, and for determining at a plurality of wavelengths covering the spectral absorption band from 560 nm to 590 nm exhibited by hemoglobin, after the egg shell colors have been classified according to an light absorbency exhibited by a pigment of an egg shell or a spectrum of light reflected from an outer shell surface of the egg, if the egg being inspected is a bloody egg in dependence on a similarity to a spectral pattern exhibited by the normal egg. 
 
   
   
     11. The egg inspecting apparatus as claimed in  claim 10 , further comprising:
 a transport mechanism enabling the eggs to be successively inspected while the eggs are being transported; 
 a first flexible optical fiber coupled with the light source; and 
 a second flexible optical fiber coupling between the light receiver and the spectral analyzing and light receiving element; and 
 whereby with an operating condition in which the eggs, a light projecting end of the first optical fiber extending from the light source and the light receiver are held stationary relative to each other while moving corresponding to the movement of the egg over a predetermined range in a direction conforming to the direction in which the eggs are successively transported by the transport mechanism, the eggs are illuminated by the source light while only the light transmitted through the egg is received by the light receiver. 
 
   
   
     12. The egg inspecting apparatus as claimed in  claim 10 , wherein the determining circuit classifies the egg shell colors according to a peak intensity of the pigment in a secondary differential curve of the spectrum of the transmitted light through the egg after a light absorbency in a wavelength region in which protoporphyrin, which is a pigment of an egg shell, does not absorb has been normalized. 
   
   
     13. The egg inspecting apparatus as claimed in  claim 10 , wherein the determining circuit is operable to determine if the egg is a bloody egg, by assaying with a correlation coefficient a similarity between a spectral pattern exhibited by the transmitted light through the egg and the spectral pattern exhibited by the transmitted light through the normal egg in a wavelength region in which blood hemoglobins exhibit light absorption. 
   
   
     14. The egg inspecting apparatus as claimed in  claim 11 , wherein the light receiver is employed in a plural number and disposed around the egg so that the light transmitted through or reflected from the egg are received by the plural light receivers and are subsequently transmitted to the spectral analyzing and light receiving unit through the associated optical fibers. 
   
   
     15. An egg inspecting method which comprises the steps of:
 projecting a white light, emitted from a light source, onto eggs; 
 receiving light transmitted through each of the eggs and spectrally analyzing the transmitted light and converting a light signal into an electric signal to provide a spectrum; and 
 measuring a spectrum of the transmitted light having passed through the egg, after a spectrum of light transmitted through a normal egg having no blood contained therein has been measured and recorded for each of egg shell colors and, subsequently, determining at a plurality of wavelengths covering the spectral absorption band from 560 nm to 590 nm exhibited by hemoglobin, after the egg shell colors have been classified according to an light absorbency exhibited by a pigment of an egg shell or a spectrum of light reflected from an outer shell surface of the egg, if the egg being inspected is a bloody egg in dependence on a similarity to a spectral pattern exhibited by the normal egg. 
 
   
   
     16. An egg inspecting apparatus which comprises:
 a projecting assembly for projecting a white light, emitted from a light source, onto eggs; 
 a spectrum converting assembly including a light receiver for receiving light transmitted through each of the eggs and a spectral analyzing and light receiving unit for spectrally analyzing the transmitted light and converting a light signal into an electric signal to provide a spectrum; and 
 a determining circuit for measuring the spectrum of the transmitted light having passed through the egg, after a spectrum of light transmitted through a normal egg having no blood contained therein has been measured and recorded for each of egg shell colors, and for determining at the entire spectral absorption band exhibited by hemoglobin, after the egg shell colors have been classified according to a spectrum of light reflected from an outer shell surface of the egg, if the egg being inspected is a bloody egg in dependence on a similarity to continuous spectral pattern exhibited by the normal egg.